The present invention relates generally to the field of fuel cells and more specifically to a sealing mechanism between a fuel cell stack and an adjacent fuel cell component.
Fuel cells are electrochemical devices which can convert energy stored in fuels to electrical energy with high efficiencies. High temperature fuel cells include solid oxide and molten carbonate fuel cells. These fuel cells may operate using hydrogen and/or hydrocarbon fuels. There are classes of fuel cells, such as the solid oxide reversible fuel cells, that also allow reversed operation. In a high temperature fuel cell unit such as a solid oxide fuel cell (SOFC) unit, an oxidizing flow is passed through the cathode side of the fuel cell while a fuel flow is passed through the fuel side of the fuel cell.
An exemplary SOFC fuel is shown in U.S. Published Patent Application No. 2007/0196704, which is hereby incorporated by reference in its entirety. These fuel cell systems generally include a large number of cells assembled into one or more fuel cell stacks in order to achieve the required power levels for a stationary power generation application. Fuel cell stacks are then stacked together to form a column of fuel cell stacks. Fuel manifolds are occasionally inserted between fuel cell stacks to direct a fuel inlet into corresponding adjacent fuel cell stacks and collect fuel exhaust after the fuel reacts in the stacks. A planar SOFC design has traditionally relied on high-temperature gas-tight face seals between a fuel cell stack and another adjacent fuel cell component, such as another fuel cell stack or a fuel manifold. Large compressive loads on the stacks make the face seals as tight as possible.
However, the face seal that connects a stack to an adjacent fuel cell component is frequently not as strong as desired. Small deformations in a column of fuel cell stacks can open the face seals and create significant leakage and force a shut down of the fuel cell system. This weakness is exacerbated in high temperature fuel cell units because of the large pressure drop between the fuel and air stream in and around a fuel cell stack.